Urgent: Test viburnum, lilacs for signs of serious disease


In The Garden

August 22, 2004|By Jon Traunfeld and Ellen Nibali | Jon Traunfeld and Ellen Nibali,SPECIAL TO THE SUN

I hear that I'm not supposed to send in leaf samples for Sudden Oak Death during the summer. What if I think my azaleas are infected? Isn't it risky to wait?

This year, yes, it would be bad to wait. Normally (Is there any normal weather any more?) the Sudden Oak Death fungus goes dormant during summer's high heat and droughts. Not this year. With our plentiful rain and cloudy days, the fungus may remain active and producing spores all summer. Owners of all lilac, viburnum, and camellia purchased in 2003 and 2004, plus azalea and rhododendron with suspicious symptoms, should order a test kit from our Web site or by calling us. Together we must stop this West Coast disease from getting loose in our state. More information is on our Web site.

As my tomatoes ripen they are getting white pithy spots underneath the skin. Are they OK to eat and can?

Stinkbugs discolor tomatoes when they pierce fruit skin, insert their mouth parts, and suck out the plant cell contents. Their salivary fluid causes the feeding area to become hard and discolor white/yellow. This injury is known as cloudy spot. The damage is entirely superficial. It is easily peeled or cut out and does not affect eating quality.

To control stinkbugs, squash their barrel-shaped egg masses laid on leaf undersides. Handpick nymphs and adults. They are shy and try to hide, though nymphs helpfully cluster together. Green stinkbugs have multiple generations each summer, brown stinkbugs only one. Many natural predators and parasitoid insects help control them. Conserve these beneficials by using only insecticides with a short residual. For infestations of stinkbugs, spray insecticidal soap or a botanical insecticide such as neem, rotenone, or pyrethrum, when nymphs first appear. Stinkbugs like thick organic mulches. Consider removing mulch where fruit injury is severe. Because adults overwinter in plant refuse near host plants, clean up all plant debris at the end of the season. Tilling lightly in fall and spring disturbs overwintering stinkbugs.

I want to seed my lawn. Will you send me a soil test? Is now a good time to seed or should I wait until spring?

Early fall is the best time to seed your lawn. The soil is still warm so germination is rapid, and autumn rains help with the watering. Also, the new grass has three seasons to mature before a Maryland summer, i.e. drought, hits.

By all means do a soil test first. Since the University of Maryland no longer has a soil testing laboratory, we suggest using one from a list of regional accredited laboratories, available on our Web page under Publications/Soil and Composting or by calling us.

Jon Traunfeld, regional specialist, and Ellen Nibali, horticulture consultant, work at the University of Maryland Cooperative Extension's Home and Garden Information Center. The center offers Maryland residents free gardening information and answers to plant and pest questions. Call the center's "hotline" at 800-342-2507 (Monday through Friday, 8 a.m.-1 p.m.) or e-mail questions to www.hgic.umd.edu. (You can also download or order publications and diagnose plant problems online).

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